The invention relates generally to continuous casting.
More particularly, the invention relates to a method of and an arrangement for cooling a continuously cast strand, e.g., a continuously cast steel slab.
In the continuous casting of slabs, particularly steel slabs, the slab is spray cooled in a secondary cooling zone after leaving the mold. To prevent crack formation on the slab surface, specific requirements are imposed on the spray cooling as regards uniformity, control of the spray intensity, adjustment to different slab widths, etc. Aside from these technical requirements, certain economic conditions such as low initial and maintenance costs, as well as low breakdown rates, must be satisfied.
The West German Offenlegungsschrift No. 2 401 263 discloses a cooling system for a secondary cooling zone which attempts to partially satisfy these complex requirements. In particular, controlled cooling is employed to avoid the formation of cracks on the slab surface. This cooling system is also intended to provide optimal results regardless of the shape and dimensions of the slab. The secondary cooling zone consists of a series of spaced support rolls on either side of the slab, and the cooling system consists of spray nozzles which spray cooling water onto the slab through the gaps between neighboring support rolls. A plurality of spray nozzles spaced transversely of the direction of travel of the slab is disposed in the region of each gap, and each nozzle is designed to direct a flat, fan-shaped spray towards the slab. The width of the sprays impinging upon the slab surface can be regulated by adjustable covers between the spray nozzles and the slab. The covers may have a sievelike, mesh-like or grate-like design in order to make these permeable to the cooling water.
Such adjustable covers require mechanically complex adjustment systems which must be remotely or manually repositioned when the slab width or the grade of steel is changed. Furthermore, the covers and their adjustment systems tend to require repairs or to be destroyed within a short period because of exposure to water vapor, thermal radiation and breakouts.